Epifaunal composition and fractal dimensions of marine plants in relation to emersion

Three macroalgae were studied: Enteromorpha sp. (Chlorophyceae), Hormosira banksii (Turner) Descaisne ( Phaeophyceae), Corallina sp. (Rhodophyceae). Fractal dimensions (D) for the outlines of the three species were 1.24, 1.07 and 1.35 respectively in the step range 0.5-5.0mm. All three species showed loss of epifauna on the falling tide; loss was greatest in Enteromorpha, least in Corallina. In Enteromorpha and Hormosira, most loss of epifauna was in the form of harpacticoid copepods; in Corallina loss was spread more evenly across the taxa. Epifaunal biomass and retention was much greater in Corallina than in the other two species, partially because of better water-retention properties. Enteromorpha and Hormosira both showed marked decreases in epifaunal diversity during emersion; Corallina did not.